


Shark Teeth

by lulu-writes (luluwrites)



Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell, Biting, Cuddling & Snuggling, Established Relationship, F/M, Foreplay, M/M, Mild Sexual Content, Post-Undertale Pacifist Route, You Know All Those Fics About Underfell Sans' Teeth? Yeah It's Like That
Language: English
Status: Completed
Published: 2018-06-30
Updated: 2018-06-30
Packaged: 2019-05-30 21:03:59
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,430
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15104846
Author URL: https://archiveofourown.org/users/luluwrites/pseuds/lulu-writes
Summary: It was a long day at work, but your response to him resting his head on your shoulder makes Sans pause and wonder if maybe he'd nicked you with his teeth. To the contrary, you seem to be very enthusiastic, and he has questionwhy.The answer, of course, delights him.





	Shark Teeth

Sans has folded onto you after a hard day at work, his phalanges working around your sides as he tips his head into the crook of your neck. There was a time where your height difference would’ve intimidated him, would’ve dissuaded him from tucking himself into you like this, all vulnerable and seeking. It hadn’t taken long into your relationship for him to realize what a stupid fucking idea that had been, and that you were the perfect size for him to fit himself under your chin, to feel your heartbeat against his temple.

You’d come home from your work a lot earlier than he had, and he’d recently swapped shifts with another worker so that your schedules aligned _just enough_ that you two would be out at the same time. Sans worked longer shifts as a security guard at the local hospital, so he would come back later, but always into your waiting arms. “Hard day?” You mutter, tilting your head down to kiss at the top of his skull, along the healed cracks in the bone, the little scars. You wrap yourself around him, your arms looping around his waist and settling on the phantom frame of his stomach, which was always a little softer than he wanted it to be, even though he was, otherwise, built like a brick house.

He sighs, opening his mouth to speak, his eye sockets shut. “AREN’T THEY ALWAYS?” His teeth move against your throat and, on the ending ‘s’, his teeth accidentally hook on the yielding skin of your neck. The fog of exhaustion immediately lifts from him as he feels your hands reflexively tighten on his waist, a little gasp that suddenly escapes your lips. Sans disengages quickly but carefully, pulling his jaw wider and scraping in the other direction, pulling away from you to look you in the eyes. “SHIT- DID I HURT... YOU...” He trails off, suddenly arrested and frozen as you try to compose yourself before his very eyes.

You lick your lips and swallow, your eyes darting away from his worried gaze. You’d flushed, something he couldn’t help but notice at this level of proximity. “No, baby, I’m fine.”

Very obviously, you are not fine.

“IF I SCARED YOU,  I THINK YOU SHOULD BE BLUNT ABOUT IT. I’M UNDER NO ILLUSIONS- I KNOW THAT I ESSENTIALLY HAVE A MOUTH MADE OUT OF KNIVES. DID I KNICK YOU? IS THAT WHY...?” He takes a hand off of your waist and gently runs it over the thin skin of your neck- it isn’t the first time and it won’t be the last time he considers how very fragile you are. When Sans feels no breaks in your skin, having just wanted to double-check in case his eyes were failing him, he looks back at you and feels his eyebrows raise. “WHY _THAT_ LOOK, DEAREST?” Your eyes half-lidded, your breathing a little rushed... He feels his soul thump against his ribcage, knows his magic and love for you has warped his eye lights into hearts.

“It’s nothing.” You protest, but it’s _something_ if you’re turned on like that. Sans’ thoughts flit over the few hours you’d been at home without him, and his curious look turns mischievous.

“CERTAINLY I’M EXHAUSTED, BUT I’M NEVER TOO TIRED FOR YOU, IF YOU GOT STARTED WITHOUT ME.” He uses the hand that’d examined your neck to cradle your face, leaning in for a kiss and thinking, stars, how lucky he is to have a lover in you. He knows that there’s no way for him to perfectly imitate a normal human kiss, but he can imitate the movements- parting his teeth and catching your bottom lip as he tilts into the kiss. Your hands trail up his spine, eliciting a shiver from him until you’re cradling the back of his skull, the heels of your hands braced under his jaw.

Then you pull him off of you. He opens his eyes (when had he closed them?), and you’re just as flushed. “Sans, uh.” Patiently, he waits for you to explain yourself, but the longer he waits, the more flustered you seem to get.

Sans feels himself grinning. “I’M PRETTY SURE WE’RE LONG PAST BEING BASHFUL. WHAT IS IT?” You duck your head a little, but it’s the kind of avoidance where he knows you aren’t genuinely uncomfortable. “WHAT IS IIIIT?”

“Sans, your teeth.” You say, vaguely, and he pulls back a little. He was _certain_ he hadn’t cut you before, but perhaps he’d cut you in the kiss. His eye lights trace over your face with a more practiced fervor, scanning you for injury. “No, Sans, you didn’t hurt me.” He doesn’t take your eyeroll to heart. “Sans, it just kinda...” You trail off. You smack your lips and pointedly look away from him, and what the look means hits him like a pillow over his head.

Giddy, laughing, he says, “NO. YOU’RE JOKING.” You cover your blushing face with your hands, and he laughs again, “I'VE TRIED TO BE INTENTIONALLY SEXY BEFORE. I'VE MADE BEDROOM EYES AND LIT CANDLES AND YOU SAT IN MY LAP AND KISSED MY PALMS. BUT THIS. THIS IS WHAT LAYS YOU LOW.” Sans grins, smug, leaning closer to you until you can feel his breath on the backs of your hands. “MY TEETH, WHICH I HAVE USED TO KISS YOU A THOUSAND TIMES AND COUNTING, ARE YOUR ABSOLUTE WEAKNESS. I AM BLOWN AWAY. I AM ABSOLUTELY CONFOUNDED.”

“You’re so mean!” You say, with no bite, and you pull your hands off of your face to push him back as he play-fights with you, pretending like he’s going to bite you. “I didn’t say anything when you got all bothered over me wearing your boots!”

“THAT’S PERFECTLY JUSTIFIABLE BECAUSE I AM ME, AND YOU’RE PERHAPS THE MOST ATTRACTIVE BEING WALKING THE EARTH _WITHOUT_ THE LEATHER BOOTS. YOU COULD MAKE ME A SLICE OF TOAST AND I COULD GET HOT OVER IT.” Perhaps it’s because you’re stoking his ego, perhaps it’s because he’s never really considered himself a monster to be desired. “BUT _YOU._ YOU’RE ATTRACTED TO MY _TEETH_.”

“Shut it! Me having a thing for being bitten and you have big pointy teeth is....!” You throw your hands up with enough gusto that you almost shake him off of your lap. “It’s simple math! Of course I’d think your teeth are sexy!”

“OH SO NOW WE’RE USING WORDS LIKE _SEXY_ , HUH?” Almost manic in his glee, he rolls onto his knees, closing the height gap and tilting over you. “I CAN’T BELIEVE YOU’VE HELD THIS BACK FROM ME FOR SO LONG. I’M REELING FROM THE POSSIBILITIES. I’M ABSOLUTELY OVER THE MOON.”

“You goober! You punk! Stop... stop laughing!” But your soft pushes are met with gentle nips from his teeth, which only serve to fluster you more. At a point, he catches the pad of your thumb between his front teeth, and you pull your hand back like you’d been burned, finally giving into the mood and laughing in surprise. “I can’t believe you’re nipping at me like a little dog! I can’t believe this made you laugh!”  

“SORRY, SHOULD I STOP SMILING? WILL IT MAKE YOU FALL INTO A SOFT PILE OF EMOTION BECAUSE OF THE DISPLAY OF MY CANINES? MAYBE I SHOULD STOP TALKING, SO YOU DON'T GET DISTRACTED BY HOW MY JAW MOVES.” He says, smugly, with a smug expression. You laugh, and Sans laughs with you, fitting himself back into the crook of your neck to muffle the sound. He feels your fingers on his skull again, pushing him just slightly, and he gets the idea. As carefully as he can manage, he opens his jaw and holds the soft curve of your neck between his teeth, biting down slowly so he doesn’t break the skin.

He’s rewarded with a soft moan and a surprised laugh, like you didn’t think he was going to go through with it. Sans smiles against the hammering of your pulse- you knew him. He never backs down from a challenge. You’re worming your hand underneath his shirt, to his ribcage, and he grunts into your neck in acknowledgement, letting go to trace his conjured tongue over the marks left. “Listen, funnybones.” You say, a little breathless, a little silly, “I don’t care if I’m all bothered, you need your beauty sleep. Stop trying to sink your teeth into me.”

“I DON’T SEE THE CONTRADICTION.” He says, his grin wolfish and wide, showing off every one of his sharp teeth. “I’M SLEEPING WITH BEAUTY. WHAT MORE COULD I WANT?”

**Author's Note:**

> hmu @ [my tumblr](http://www.skelezbian.tumblr.com)!
> 
> Request: "may i request a saucy little number with reader complimenting black’s teeth?" from my friend ali! and, Oh Boy, You Can Request It, Ali


End file.
